Carrying a GPS unit on/in backpack

There's a thread about GPS accuracy that talks about this

I've tried clip and concluded the same thing – can fall off, but someone else uses it successfully – try it yourself.

If you had a pocket on the shoulder strap that could hold it, that would work

I just carry in pocket, but like you said, it's sort of bulky and heavy so non-optimum

I clip my etrex 20 to a webbing loop on my shoulder strap using a small S-biner. I just hook it through the quarter turn fastener on the back of the battery door. A few hundred miles with this setup with no issues.

Depending on the capability of the receiver, you may be able to stick it inside your backpack. I use a Delorme PN-60 and often carry it inside my pack and it has no problem keeping contact with the satellites.

I think they also make belt holsters, that might be an option. You could strap it to your pack, if you didn't want to carry it on your hip.

Does it flop around when clipped?

I have mine on a short leash (~6") and clip the free end to a loop on my shoulder strap. Then I toss the unit (eTrex 20) behind my neck on top of my pack. It does have a tendency to slide off if you lean way forward, like to pick something up off the ground, but the lanyard keeps it from harm. And when I need it I just give the lanyard a pull, no need to unclip anything.

Adam

I put a small zip tie on the GPS so I'd have an easy loop to attach to. I use a small s – biner and attach it to my chest strap so I can easily read it.

It doesn't flop around as the loop and biner are small, so very little play.

I don't find that it flops around much at all. I don't really notice it while hiking, but I should mention that I use this setup for on-trail hiking. If I'm bushwacking (which is usually only when I'm fishing), I tend to just leave it in my bag since I mainly just use it to mark good locations along the river and am not concerned with checking it regularly.